Integrated Dispatch Enhanced Network (iDEN) is a wireless technology combining the capabilities of a digital cellular telephone, two-way radio, alphanumeric pager, and data/fax modem in a single network. iDEN operates in the 800 MHz, 900 MHz and 1.5 GHZ frequency bands and is based on time division multiple access (TDMA) and global system for mobile communications (GSM) architecture. The iDEN protocol provides 25 kHz channels which are divided into six time slots.
In the iDEN protocol, there is a continuous stream of data in the outbound direction which is received and processed by a mobile station (MS). Often the data contains no significant information, for example, when a person using a first MS at one end of an iDEN communication link pauses during a conversation. During the pauses, comfort noise parameters are generated by the first MS and passed to a second MS in a time slot referred to as a comfort noise slot. The comfort noise parameters typically contain audio coefficients of the background noise of the environment where the second MS is located.
The comfort noise slot is typically followed by up to seven fill slots. The comfort noise slot and seven fill slots constitute a data block. To preserve battery life, the first MS typically does not transmit data during the fill slots. Hence, an uplink data block being uploaded by the first MS typically contains empty fill slots. To generate comfort noise at times correlating to the fill slots, comfort noise generated from the comfort noise parameters is repeated. The comfort noise parameters are re-generated and transmitted for every uplink data block until the person begins speaking again. Significantly, the fill slots in each data block represent wasted bandwidth since they are not being used to carry a data payload.